Hat Tip from Stanley D. Baum - Article Here
"The IRS said that the doctrine of constructive receipt applies to the "salary advances" to employees. Accordingly, an employee would be required to include the amount available as a salary advance in gross income in the earliest open tax year in which the advance was available (even if not taken), and this amount would be subject to income tax withholding at such time as a constructive payment. The IRS continued by saying that, even if there was no constructive receipt, salary advances which an employee is expected to earn through future services are taxed as compensation, and are therefore included in gross income, at the time of receipt. The IRS conceded that an (unspecified) employment tax exception would apply to an employee, so that any advance would not be subject to employment tax. Further, if there is no constructive receipt, the salary advance program causes the Plan to violate IRC Section 409A, due to the permitted off-set feature described above. Apparently, the IRS felt that this offset, which is a pre-employment termination use of amounts deferred under the Plan, causes an acceleration of the payment of deferred compensation by the Plan, and this acceleration violates Section 409A."